okeh, originally a Choctaw affirmation, which was said on the end of every important sentence, m'kay. It must have been fairly addictive, m'kay. Later, Oklahoma was named OK by the postal service, m'kay. Then there was a Choctaw town, renamed to Okay, OK, m'kay.

You reckon it was a coincidence that a bunch of people who said OK all the time, suddenly got to live in a state called OK?

Later, OK was reverse engineered in 1840 by gr8 1eet speekers, to mean "oll korrect". The Boston slang idea was then popularised by white people as the true origin of OK.